Flight computer



Sept. 7, 1948. L. w.. IMM 2,448,596

FLIGHT COMPUTER Filed April 21, 1942 7 Sheets-Sheet 1 DEAD RECKONING COMPUTOR TRUE cougsz 0500M; SPEEID MPH. 100 200 300 I 400 500 AIR 45 FE'E %OOO TEMPESATURE. 300' v TRUE TIME 0 5 00 45o FIGI INVENTOR. LEWISW. IMM

BY W Sept. 7, 1948.

Filed April 21, 1942 L. W. [MM

FLIGHT COMPUTER '7 SheetsSh est 3 IN VEN TOR. LEWISW. IMM

Sept. 7, 1948. L. w. lMM

FLIGHT COMPUTER '7 Sheets-Sheet 4 Filed April 21, 1942 FIGEBB INVENTOR. LEWIS.W.IMM BY W2 6;

FIG?

L. W. [MM

FLIGHT COMPUTER Sept. 7, 1948.

7 Sheets-Sheet 5 Filed April 21, 1942 INVENTOR. LEWIS. w. IMM BY W-M FIG-.8

p 1948- L. w. IMM 2,448,596

' FLIGHT COMPUTER Filed April 21, 942 I 7 Sheets-Sheet 7 INVENTOR. LEW|S.W. IMM

Patented Sept. 7, 1948 FLIGHT COMPUTER Lewis W. Imm,

Glendale, Calif.,

assignor to Librascope, Incorporated, Burbank, Calif a corporation of California Application April 21, 1942, Serial No. 439.874

11 Claims. 1

The present invention relates to computing mechanisms and more particularly to the provision of correlated but individual computing devices capable of solving various portions of a complex problem which may involve, for example, the solution of various equations, solving one or several triangles to find the values of unknown sides or angles, the conversion of polar to rectangular coordinates, and other computations.

The computations involved in aircraft flight problems are complex computations of this nature, and the invention is disclosed as embodied in a flight computer because it is important to provide a computer which will rapidly and accurately solve such problems While in flight. It will be understood, however, that many of the subcombinations disclosed herein are useful in computing devices designed for other or more general uses.

A principal object of the invention is the provision of improved mechanisms for solving equations of a complex nature.

A further principal object of the invention is the provision of a novel mechanism for computing the conversion of polar coordinates to rectangular coordinates.

Further and more specific objects of the invention are the provision of triangle solving mechanisms by which, given the values of two sides and a non-included angle the Value of the other non-included angle or the value of the third side may be computed.

Additional specific objects of the invention include solving for value of true airspeed, drift angle, distance travelled in a given time and similar values, from known or indicated data available to aircraft pilots.

Other objectives and advantages are given in the detailed specification and claims which follow. The invention may be better understood by referring to the attached drawings in which:

Fig. 1 is a view in frontal elevation of the control panel of an instrument embodying the present invention.

Fig. 2 is arear view of the complete computing mechanism.

Fig. 3 is a rear elevational airspeed and time mechanisms.

Fig. 3A is a rear view of one of the multiplying mechanisms shown in Fig. 3 with the parts being in diiierent positions.

Fig. 3B is a side elevational view showing View of the true one of the actuating springs and associatedparts 2 designed to urge its associated pointerin the-desired direction.

Figs. 30, 3D, and 3E are rear elevational views of three of the multiplying mechanisms shown in Fig. 3 with the parts being in different positions from that shown in Fig. 3.

Fig. 4 is a rear elevational view of the wind direction and wind velocity mechanisms.

Figs. 4A and 4B are rear elevational views -of two of the multiplying mechanisms shown in Fig. 4 with the parts being'in different positions.

Fig. 5 is a rear elevational View of the altitude and air temperature mechanisms.

Fig. 6 is a detailed cross-sectional view of one of the setting knobsand the parts immediately actuated thereby. v

Fig. 6A is a view similar to Fig. 6 but taken at right angles-thereto.

Fig. 7 is a frontal view of the true course disc and the wind direction knob. I

Fig. 8 is a geometrical diagram to show'the relationship of certain angles and lines.

In Fig. 8 is shown a geometric figure to better understand some of the problems involved and the solution thereof. In this figure the line AN represents a true north and south-line. Suppose the wind is blowing from B in the direction A or at an angle W relative to AN, and at a velocity Vw in a unit of time equal to the length of the line AB. The desired course to be flown is in the direction E from the point A, making an angle C, with the line AN. The plane would be directed along this path if there were no wind to cause it to drift. Suppose we desire to follow the line AE to the point F in a certain unit of time. Call this distance AF (Vg) Vg is then the true course ground speed in miles per hour. Draw F0 from point F equal to and parallel to AB. Draw OB which will be parallel and equal to line AF. Draw a perpendicular from the point 0 to the line AF, extended if necessary, meeting the line AF at the point 'E so that the angle E is a right angle. If F is between the points A and E then EA equals V -l-EF. If the point E lies between A and F; that is, if F is beyond the point E, th6IIEA=Vg-.EF. ThereforeEA equals VgiEF. Draw the transversal A0 of the parallelogram AFOB. Call this transversal Va, representing the velocity of the plane, with respect tothesurrounding air Va being the resultant of the forces which are represented by the lines AF and AB. Line A0 then represents the direction in which the plane must be headed to compensate for the wind com 'dition. Call the angle FAO (D) which represents the drift angle and gives us the correction which we must make to true course to establish airplane heading A0. Call the angle EAB (C-W) which simply gives you a negative value for what would have a positive value in degrees if the expression had been (W-C). Since the line F is parallel to AB and cut by the transversal EA, the angle EFO is equal to (C-W). C, W, and Vw are known quantities which are set up on the apparatus. Va is a function of indicated air speed, temperature and altitude; all of which are known. A subsidiarycomputing mechanism is provided in the apparatus whereby Va can be set up therein after the 4 thus permitting the feeding in of the relatively small quantity:

Va(O -1) as a corrective factor.

It having been ascertained that:

where f(h, ta) represents a function of altitude and air temperature; it becomes necessary only to multiply this function by Va in order to compute the quantity to be added, as a correction, to Va to compensate for changes in air density at various altitudes and temperatures.

setting of temperature and altitude factors by Therefore, EO=Vw sin (C'- W).

In the triangle AEO sin D= Therefore,

Si. D Vw g so that D=sin-1 f Formula #1.

In triangle FOE,

Cos o- W) Therefore, EF=Vw cos (C-W).

In triangle EAO,

Therefore,

Therefore,

V cos (C' W) V,,-- V,,{cos D i this formula is alternatively expressed:

Vi=Va+Va(0' -1) (Formula No. 3)

But,

Also, the total distance (d) is the true course ground speed Vg multiplied by time (t) or d=V t.

v Formula #4.

In all the four formulae above, V =true course ground speed in miles per hour.

Va=true airspeed in miles per hour.

D= drift angle in degrees.

Vw=wind velocity in miles per hour.

C=course or track to be flown in degrees; i. e., the course that would be flown by the plane if there were no drift.

W=wind direction in degrees.

V1=indicated airspeed in miles per hour.

e=density ratio of air under actual conditions which, of course, is controlled by altitude and air temperature.

d=tota1 distance in miles.

t=time in hours.

All of the setting knobs or item-entering devices, as well as all of the links, levers, and other movable parts, are mounted on a main panel I51. The face plate I5? is spaced a slight distance in front of the panel I51, providing suflicient space therebetween for the various pointers.

In Figs. 6 and 6A the setting knob I59, which is typical of all of the setting knobs I63, Ida, H5, IE'I, I258, and II, is afiixed to shaft I58, rotatably mounted on panel I57. On the back of panel I57 a pinion Ififi is secured to the shaft I58, which pinion meshes with and drives a rack I BI, which is maintained in mesh with the pinion I60 by means of a spring clip IE2. The rack it?! carries a plate I13, to which is secured a pullpush wire I Hi. The arrangement is such that rotation of the knob I 59 will reciprocate the rack I6I, and, in order to prevent inadvertent displacement thereof after the knob I59 has been set, the spring clip I62 presses the rack IIiI into engagement with pinion Itiil, thereby creating sufficient friction to prevent movement of the rack I6! or the wire I74 unless knob I59 is positively rotated. All of the setting knobs shown in Fig. 1 operate racks and wires similar to the above described mechanisms in Figs. 6 and 6A.

True airspeed knob and mechanisms controlled thereby The true airspeed factor Va is set into the instrument by rotating the true airspeed knob I63. As shown in Fig. 3, rotation of the true airspeed knob I63 turns gear pinion I, corresponding to pinion IEII, which moves rack 2, corresponding to rack I ESI. At this point the motion splits into two parts, one part following wire 4 and the other part following the movement of pin 1 carried by the lower end of rack 2. Wire 4 is secured to the plate H5 which corresponds to the plate I13 of Fig. 6.

The pin "I actuates the lever B an amount corresponding to Va. The lever 6 turns on pin 22 which is carried by the link I42, Fig. 4. While it is true that the .pin 22 is actuated, by the wind direction and wind velocity knobs, as will be hereinafter described, the pin 22 is stationary while only the pinion l is rotated, so that it may be considered as a fixed pivot pin. As pin l moves upwardly or downwardly, as above described, it moves lever 5, the pin I serving as a means to connect the lower portion of rack 2 to both levers 5 and 6. The lever 5 is pivoted on pin it}, which is movably supported by wire E9 and which is given a movement corresponding to 1&(016 l), as will be hereinafter described. The lever 5 carries the pin 9 intermediate its ends, the wire 8 extends upwardly from the pin The lev r 5 is an addition lever which adds the value Va received from pin l to Va (ct-l) received from pin H3 so that the wire 8 is given movement corresponding to which is indicated airspeed Vi. Formula 3. Motion is transmitted. from wire 8 to lever it through pin with lever l I havin a fixed pivot on the 53 carried by the panel I51. Lever l 5 moves wire Ed by means of pin l5. Wire 54 carries stop H5 at its upper end above disc Ell through which the wire slides. The disc ill is rotatably mounted on pin l? carried by lever it, which is secured to shaft 28, to which is attached the indicated airspeed pointer 59.

A conventional coil spring I18, 8B, is wound about shaft 58, having one end connected to the panel and the other end embedded in nut lee secured to shaft -3, so as to urge lever H3 clockwise or towards the stop 5'58. It is therefore, apparent that a lost motion connection is provided between the wire 5-4 and lever l6. When the wire it moves upwardly, with the lever 55 spaced below the stop IE3, the lever 18 moves clockwise and the disc ill is held against stop 27% by means of the spring H5. The lever 56 engages the stop '23 when pointer 59 is at the lowest reading of the indicated airspeed scale. However, the wire 5 may continue its upward movement even after the lever I5 is stopped by the stop Hi3, but in this case the wire l4 simply slides through the hole of the disc ill so that stop would travel away from the disc ill and no motion would be imparted to the lever l 5 or pointer is. When the wire M is then moved downwardly it would impart no motion to the lever 55 until the stop E76 engages the disc ill, and thereafter the downward movement of wire Hi would rotate the lever it and the pointer l9.

It will be remembered that lever 13, pivoted on pin 22, is also actuated by movement of the rack 2 by which the lever 6 is given a movement of Us at pin As will hereinafter be explained, the pin 22 is given a movement corresponding to Vw cos (CW). Lever 6 carries pin 2! on which lever 29 is mounted and this pin is therefore moved an amount corresponding to Vrrl-Vw cos (CW The lever carries movable pin supported by the lower end of wire H, which is also movable when the pinion I is actuated and is given a movement corresponding to Va (cos E-l as will be hereinafter described. Lever 29 is provided with pin 24, the movement of which will, therefore, depend upon the mov ment of both pins 2! and 25 and hence will be moved an amount corresponding to which is V or true course ground speed in miles per hour. Formula #2. Pin 2 actuates wire 23 which moves lever 25 by means of pin 2?, with lever 28 having a fixed pivot pin 28 secured to 6 the panel I51. into two parts, one part following wire 29 through pin 39 and the other part following wire 3| through pin 32.

Rotatable on pin 32, carried by lever 26, is a disc 53! having a hole through which extends a wire 3! which carries a stop I82 below the disc 58!, which stop is resiliently held in contact with disc till by means of the spring I83 coiled about wire El and interposed between a stop I84 on wire 3i and disc 85. The disc I85 is rotatably mounted on pin 3 carried by lever 33 secured to shaft 35. The disc H85 is provided with a hole through which the wire 3i extends and the wire M is provided with a stop I85 below the disc 5 A coil spring, identical with spring lid, is coiled about shaft 35', having one end embedded in panel l5! and the other end connected to a nut similar to nut lBi! secured to shaft which carries the true course ground speed pointer 35. As above stated, the rod 28 ctuated by the pin 24 an amount corresponding to true course ground speed or Vg, and this vement is transmitted to pointed 36 by the above described. The lever 33 has a tail g beyond the shaft 35, and when the true course ground speed pointer 36 is at its lowest reading of its scale, the said tail contacts the fixed stop N58. The coil spring around shaft 35 urges the lever 33 clockwise so as to urge the tail into engagement with the stop I88 and so as to urge the disc H35 into engagement with stop E86 on wire 34. The objective of the above de scribed lost motion connection is to stop pointer at its lowest reading relative to its scale while allowing lever 26 to continue its downward movement.

It will also be remembered that when lever 26 is actuated it moves a wire 29 by means of the pin 38 an amount corresponding to Vg. The upper end of the wire 28 is connected to a bell crank lever El by means of pin 38. The bell crank lever 3'5, Figs. 3 and 3A, has a fixed pivot pin 35;, and the said lever extends upwardly beyond the pivot pin to the pin M. The link is also hung on the pin ll, and the lower end of the link 4i carries a pin 42 connected to ks 'l l and The link 3 is pivoted on pin carried by the upper end of lever HM mounted on a fixed pivot iii-3, which lever tile is connected to rod m3 by means of pin I05. The rod I63 is connected to rack Hi2, geared to pinion l9! actuated by the time knob I54 so that the pin t? is given a movement corresponding to time 1?. The link M is connected to the lever 4'! by means of pin it, lever i! having a fixed pivot on pin carried by panel I51. A spring 3 is 1%) connected to lever 3'? so as to tend to rotate the said lever in a clockwise direction to take out any possible backlash. The parts including the links it, l and 37 of Fig. 3A is a multiplyi 1g mechanism by which the value f or time entered by means of link 43 is multiplied by true course ground speed V entered through lever 3'1, which product is total distance d. Formula #4.

[is shown in Fig. 3, the pins 39 and 42 are in al gnment with each other. In such a case, the rotation of the bell crank lever 31 moves pin ll and lever 69 without moving link 44. This condition would occur when the time setting knob .34 is at zero. However, when the time setting imob 55 i is actuated the lever IE4 is moved, moving the pin to, as will be hereinafter described, so that pin 42 is moved out of alignment with This condition is shown in Fig. 3A.

At this point the motion splits Considering the parts in the position shown in Fig. 3A, it is apparent that if lever 31 were moved clockwise on pin 39, pin II will be moved in an arc of a circle having a radius equal to the distance between the pins 39 and 4|. Since the pin 55 is not being moved it may be considered as a fixed pivot for it will not be moved until the time setting knob I66 actuates it. Therefore, the pin 52 can only move in an arc of a circle having a radius equal to the distance between pins 35 and 32. Link 49 will therefore, move downwardly. As pin 42 moves downwardly with link 49, link it will be pulled downwardly, and the bell crank lever 41 will move anti-clockwise on its fixed pivot pin 48. These motions, of course, will be reversed when the bell crank lever is moved anti-clockwise.

The bell crank lever 41 at its other end carries a pin 59 which will be moved an amount corresponding to total distance d as above described. 011 this pin 59 is rotatably mounted a disc I89 having a hole through which passes the wire 59, carrying stop I99 below the disc I89. As there is extremely little lost motion at this point the wire 59 may be considered as a link suspended from pin 59. The wire 59 is connected to lever Si by pin' 52. The lever 5i is secured to shaft 53, on which is secured the total distance pointer 54. A coil spring, similar to spring I19, surround-s shaft 53, and tends to urge the .pointer 5 t towards its highest reading.

It will be remembered that, when the pinion I is rotated, the wire 4 is raised. The link 55 is rigidly attached to wire 5, and at its upper end carries a wire I9I slidable through a hole in a guide I92. The link 55 actuates link 56 through pivot pin '51, link 58 through pivot pin 59, and link 59 through pivot pin 6|. All of the pins 51, 59, and El Will be actuated by link 55 an amount corresponding to Va.

The link 56 Figs. 3 and 30 carries pin 64 at its upper end, which pin is connected to links 52 and 93. Link 63 is connected to bell crank lever 61 by means of pin 55. The bell crank lever 51 is pivoted on fixed pin 6. Link 52 is connected to link I52 mounted on a fixed pivot pin E53 by means of pin 65, which pin, as will be hereinafter described, passes through the upper end of wire I59, which may be shifted by either the altitude knob or the air temperature knob and which wire I59 is given a movement corresponding to r% 1, as will now be explained. The altitude factor is set into the instrument by manually operating the altitude knob I53. As shown in Fig. 5, rotation of the altitude knob E58 turns the pinion 2M which moves rack 292 which carries wire 293. Wire 203 moves lever M1 through pin M8, with lever I41 being pivoted on a pin 59, which may be moved by the air temperature knob I1. The air temperature knob I19 actuates pinion I54 which actuates rack E55, carrying wire I56 connected to pin I49. Therefore, when pinion I54 is actuated the lever M1 has a fulcrum on pin I58, and when pinion 2IiI is actuated the lever I41 has a fulcrum on pin m9. Lever M1 carries a pin I5I which actuates the wire I59, which is connected by pin 55 to links 52 and I52, constituting a part of the multiplying mechanism described in connection with Fig. 30. As explained in connection with Formula 3, v -4 is a function of altitude and air temperature, and the wire l5 and pin 65 are therefore actuated an amount corresponding to a' 1.

This multiplying mechanism shown in Fig. 3C

8 multiplies the value Va entered through pin 51 by Ira-1 entered through wire I59. As shown in Fig. 3, pins 55 and 6B are spaced only a short distance apart. If the pin 65 were in alignment with the pin 56, and the link 55 were actuated to move links 62 and 63, no motion would be imparted to the bell crank lever 61. But the pins 55 and 55 may be moved a considerable distance apart, as shown in Fig. 30, by the altitude and air temperature knobs. As shown in Fig. 30, the upward movement of link 55 moves the pin Ii l upwardly, thereby moving the lefthand ends of links 52 and 69. Unless the wire I59 is also shifted, the pin 65 may be considered as a fixed pivot for it is held against vertical movement by wire I59 and against lateral movement by link I52, so that the pin 54 will describe an arc of a circle having a radius equal to the distance between the pins 64 and 55. As pin 64 moves upwardly on this are it pulls the link 63 and rotates lever 51 clockwise. On the downward movement of pin lid the motion described above will be reversed. Obviously if pins 65 and 55 were in alignment, the upward or downward movement of link 55 would impart no movement to lever 51. The greater the distance between pins 65 and 55 the more movement will be imparted to lever 51 by the raising or lowering of link 55. These parts therefore, constitute a multiplying mechanism so that the movement of lever 51 is dependent upon the movement of link 55 and the movement of wire I59 to position pin further from or closer to pin 96.

Lever 51 moves wire 59 through pin 19'. Wire 59 moves lever 5 through pin l9 and this movement is Va r%1). It is, therefore, apparent that both ends of lever 5 are shifted when the pinion I is rotated. The lefthand end or pin 1 is shifted by rack 2 an amount corresponding to Va, and the righthand end or pin II] is shifted by wire 99 an amount corresponding to Va (a%1). The pin 1, therefore, moves a distance exactly corresponding to the rotation of pinion I, while the pin Ii] is moved a distance corresponding not only to the rotation of pinion I but varied in accordance with the position of pin 65 relative to pin 56, which pin I55 is adjusted by the altitude knob I58 and the air temperature knob I10, as heretofore described. The lever 5 is an addition lever, so that the pin 9 will move an amount corresponding to Va+Va (a %l), which is the indicated air speed (Vi) as set forth by Formula No. 3. As heretofore described, the pin 9 is connected to the indicated airspeed pointer I9 through lever I I.

It will be remembered that link 58, Fig. 3D, moves with link 55 an amount corresponding to Va. Link 58 moves links 1 and 'II by means of pin 12. Link 19 is pivoted to arm 15 by means of pin 13 and link 1! is pivoted to lever 91 by means of pin 14, lever 91 having a fixed pivot pin 99 carried by the panel I51 and arm 15 being mounted on a fixed pivot 15. The lever 91 carries a pin 98, on which is hung a wire 9I, which wire 9| may be raised or lowered by the partial rotation of the lever 85. The essential point is that the raising or lowering of wire 9I rotates the lever 91 on its fixed pivot pin 99 an amount corresponding to cos D-l to move the pin 14 into or out of alignment with pin "I3, the value cos D1 being zero when pin 15 is in alinement with pin 13. When wire 9! is raised it moves pin 98 upwardly and rotates lever 91 clockwise on its fixed pivot pin 99, and moves pin 1 1 downwardly, thereby varying its distance from pin 13. When 9 pins 13 and 14' are in alignment with each other and link 58 is raised or lowered, no movement is thereby imparted to arm 15, which has a fixed pivot 18; but the further the pin 14 is raised or lowered, relative to the pin 13, the greater is the movement which will be imparted to arm 15 by movement of the link 55. Here again we have a multiplying mechanism depending on the movement of pinion I and on the movement of wire 9|, which is controlled by the movement of lever 83, as will be hereinafter described.

This multiplying mechanism multiplies the value V5. entered through link 58 by cos D-l entered through lever 91. The true airspeed lmob I63 through pinion I, as well as the wind direction knob I55, and the wind velocity knob I61, controls the movement of the lever 83.

Arm 15 moves wire 11 by means of pin 18'. Wire 11 is connected to lever 29 by means of pin 25. It is, therefore, apparent that lever 20 is controlled by both pins M and 25, that pin is controlled by the position of the wind direction knob I65, as well as by the movement of the true airspeed knob I83 and the wind velocity knob I61 to enter the product Va (cos Dl), while pin 2I is actuated an amount corresponding to Va-I-Vw cos (CW) because it is controlled by the movement of both .pin 1 and pin 22, the pin 1 being controlled solely by the true airspeed knob I63 and hence introducing the value Va, While the pin 22 is controlled by the wind direction knob I 65 and the wind velocity knob I81 and entering the value Vw cos (C-W), as will be hereinafter described. The actuating of wire 23 by pin 24 is, therefore, dependent upon all of the above factors so that this wire moves an amount corresponding to Va (cos D1)+Va+Vw cos (C'W), or true course ground speed, which is Vg. Formula #2; and it will be remembered that it is the wire 23 that actuates the true course ground speed pointer and the total distance pointer 54, as heretofore described.

It will be remembered that the vertical movement of link moves the pin 6] and link upwardly or downwardly an amount corresponding to Va. Referring to Fig. 3E, it will be noted that the pin 88 connects links 18 and 19 to the upper end of link 88. The other end of link 18 is connected to lever I21 by means of pin 8|. The lever I21 has a fixed pivot pin I29 and may be partially rotated on its pivot pin I29 by the movement of pin I28, which is actuated by the rotation of the wind direction knob I85 and the wind velocity knob I91 an amount corresponding to Vw sin (CW), as will be hereinafter described. The righthand end of link 19 is connected to lever 83 by means of pin 82. The lever 83 has a fixed pivot pin I89 carried by panel I51, which lever extends beyond the pin and at its lefthand end carries a pin 85 on which is mounted disc I93. This mechanism shown in Fig. SE is a division mechanism which divides Vw sin (C-W) entered through pin I28 by Va entered through link 60. However,

Formula #1. As shown in Fig. 3, the pins 8| and. 82 are in alignment with each other, and the vertical movement of link 55 will partially rotate links 18 and 19 without imparting any movement to lever 83. As will be hereinafter explained, if the wind direction knob I were rotated clockwise from the position shown in Fig. 1, for 90, and if the wind velocity knob I61 were set to represent a value, the lever I21 will be actuated so as to move anti-clockwise, thereby moving pin M to the right. It pulls link 18 and moves pin 88 to the right, thereby pushing link 19 and rotating lever 83 clockwise. If the wind velocity knob I61 were set at zero the rotation of knob I65 would not move the lever I21, as will be hereinafter described. Since link 19 is connected to lever 83, and since lever 83 has a fixed pivot on I00, the pin 82 is moved downwardly to the position shown in Fig. 3E. If then the link 55 were actuated, movement would be imparted to lever 83. The extent of this movement would depend on how far link 55 was moved and how far out of alignment were pins BI and 82, and this would depend on the setting of the wind direction knob I and the wind velocity knob I51.

If the wind direction knob I65 had been rotated anti-clockwise instead of clockwise, as above described, and if the wind velocity knob I61 were moved to represent a value, the pin 82 would be moved above the pin M, as will be hereinafter described. The wind velocity knob I61 and the wind direction knob I65 control the position of pin 8|, while the true airspeed knob I63 controls the link 55. This is a division mechanism having as its factors true airspeed, wind velocity, and wind direction.

The lefthand end of lever 33 is, therefore, moved upwardly or downwardly, as above described an amount corresponding to the value of sin D, carrying the pin 85 and the disc I93 with it. A wire 84 slides through a hole in disc I 93. The wire 84 carries a stop I94 below the disc I93 and a stop I95 spaced a distance above the disc I93, with a spring I99 coiled about the wire 84 and interposed between the stop I95 and the disc I93. The lower end of wire 88 passes through a hoie in disc I91 mounted on pin 81, and carries a stop I98 below said disc. The wire 84 also carries a stop I99 spaced above the disc I91, and a spring 298 is coiled about the wire 84 and is interposed between the stop I99 and disc I91.

There is, therefore, a lost motion connection between the lever 83 and the wire 84, and also between the wire 84 and the disc I91. The disc I91 is mounted on a pin 81 carried by bell crank lever 85 pivoted on a fixed pin 88. The lever 89 is connected to the lower end of wire 9| by pin 92, which wire 9I, as above described, is connected to lever 91, which controls the relative position of pins 13 and 14 and, therefore, controls the degree of movement which will be imparted to wire 11 when link 55 is moved by pinion I. In Fig. 3 it will be noted that the angle formed between the lines passing through the points 81 and 88 and 88 and 92 is slightly more than a right angle. If it were a right angle, then the vertical movement of sin D given to the pin 81, as heretofore described, would impart a 'vertical movement to rod 9i through pin 92 of cos D, but since the said angle is slightly greater than a right angle, the said vertical movement of the rod 9| is cos D-I, which movement is transmitted to the pin 98 of lever 91. Also, it will be remembered that the link 58 of Fig. 3D entered a value of Va, and that the multiplying mechanism of that figure actuates the rod 11 an amount corresponding to their product, which is Va (cos D-l). Since wire 11 controls the variable pivot pin 25, it thereby controls in part the true course ground speed pointer 36 and the total distance pointer 54.

The lever 86 also carries a pin which actuates wire 89 which moves arm 93 by means of pin ll 94. Arm 93 turns the drift angle pointer shaft 35, to which is attached the drift angle pointer 95, Fig. 1. Since the vertical movement of pins 8 'I and as of lever 86 correspond to the sin value of the drift angle D, as above described, the arm 93 converts this sin movement into the angular value of the drift angle D.

True course disc and wind direction knob The true course disc I66, Figs. 1 and 7, is merely a compass rose. The true course disc I63 is manually turned about its pivot and moves none of the linkage mechanism whatsoever.

The wind direction disc Ill .is rigidly attached to the wind direction knob I65. The difference between the true course angle and the wind direction angle (CW) is accomplished with the true course disc I tfi and the wind direction knob I65. The procedure is as follows: The true course disc I66 is rotated manually so; that the Value in degrees of the true course is directly indicated by the true course arrow IlE. For example, in Fig. 7-, 30 was indicated as the true course. Th wind direction knob IE is then rotated to indicate the wind direction relative to the true course disc I66. As shown in Fig. 7, 60 is indicated as the wind direction. The Wind direction knob I55 is secured to shaft Itl which carries crank I88. When the wind direction knob IE5 points directly to the fixed arrow I12 the crank use on crank shaft; IIi'I is in its zero position. It can now be seen on Fig. '7 that the wind direction knob Ida has been positioned at an angle of 30 relative to the true course disc I66, this being the difference between the true course angle and the wind direction angle. In other words,

and places the proper rotation into the mecha-' ind direction and wind velocity knobs and mechanisms controlled thereby As above described, the knob E65 rotates the crank me an amount corresponding to C-W. Crank Itil actuates wire I59 by means of pin H8 and also moves wire III by means of pin H2. It will be noted in Fig. 4 that the imaginary lines between the points IIQ and IE? and II2 and It? form a right angle at point Ili'l, and that when the crank is in its zero position, as shown, the wire II I is parallel to the line between the points I91 and I I2. Therefore, the movement imparted to the wire I M will be sin (C-W) and the move ment imparted to the wire I I I will be cos (C-W) Wire IfiIl actuates link H3, Fig. 4A, by means of pin IIIl with link II 3 having a fixed pivot IIE'i. Link I I3 is connected to link I I5 by means of pin I1. Link H6 is connected to links H8, M9 by means of pin I23 with link H8 being pivoted on pin I2I carried by reciprocating link I lii and link I It being pivoted on pin I22 carried by lever I23, which lever I23 is mounted on a fixed pivot I24. The link I it is actuated by the wind velocity knob I61 through pinion I 43, rack Idiiand wire I45 an amount corresponding to Vw so as to vary the distance apart of pins H5 and I28, thereby entering the value Vw or the wind velocity into the multiplying mechanism shown in Fig. 4A, and the rod I09 enters the other multiplying factor sin (C-W). Lever I23 is the output for the multiplying mechanism and is therefore actuated an amount corresponding to Vw sin (Ci-W). Lever I23 actuates wire I25 through I 26. Wire I 25 actuates lever I2? by means of pin I28, the lever I21? having a fixed pivot I29. As heretofore described in connection with Fig. 3E, lever l2?! actuates link'lil through pin AI, and the output from the division mechanism shown in said Fig. 31-3 is the rod ii l which is actuated an amount corresponding to V sin (0- W) t will be remembered that the rod ii -i leads to mechanism controlling the drift angle pointer 96, the true course ground speed pointer and the total distance pointer M.

It will be remembered that when the wind di rection knob I55 is rotated, thereby rotating crank I68, wire II I is actuated an amount corresponding to cos (C- N) The wire I I I moves link I38, Figs. 4 and 43, by means of pin Iiil, with link lad having a. fixed pivot pin Link I36 is' connected to link I33 through pin Iii-4i. Link I33 is connected to link I35 and link IEIS through pin Isl, with link I35 being pivoted on pin I38 carried by link l ili, which is actuated an amount corresponding to Vw by the wind velocity knob Ifii'. Link I35 is connected to the arm M6 by means of pin I39, with arm its having a fixed pivot pin i i-I. Arm moves wire Hi2 through pin I-E'.

Here again we have a multiplying mechanism which moves the wire according to the factors of wind velocity and wind direction. The link I35 introduces the factor Vw and the rod I I I, the factor cos O-VJ) This multiplying mechanism multiplies these factors and actuates the output rod M2 leading to the pin of lever 5, Fig. 4, an amount corresponding to Vw cos (Cll7). If the wind velocity knob Ifil is at zero, the pins Iii? and I32 will be in alignment, as shown in Fig. 4., and rotation of the wind direction knob W5 will impart no motion to the arm or to the wire Hi2. When the wind velocity knob I5? is rotated to its maximum value the link I ls is raised, thereby moving pin IS? a considerable distance from the fixed pivot pin as shown in Fig. iB. If new the wind direction knob E65 were rotated from its vertical position, the wire Hi2 will be actuated according to both the wind direction and the wind velocity. When the wind direction knob I is rotated 99 from the position shown in Fig. 1 either to the right or to the left, the wire III will move link It'll so that the position of pins Ida and I39 are in alignment with. each other. If now the wind velocity knob It? were rotated from its zero position, no motion would be transmitted to wire hill; but when the pin I34 is spaced below the pin I39 as shown in Fig. 4B, or in case the pin IN is spaced above the pin I359, which would be the case when knob IE5 is rotated 180 from the position shown in l, and if the wind velocity knob iii? were then rotated, motion would be transmitted to wire I 52.

Wire I i2 moves lever 6 by means of pin 22, lever B turning on the pin i. The reason why no motion is transmitted to wire M2 and lever B when the wind direction knob IE5 is rotated from the position shown in Fig. l is because the wind would be blowing at right angles to the plane, and neither advancing or retarding its speed. It is, therefore, apparent that the lever B is controlled in part by the wind velocity and the wind direction, and these elements are, therefore, to be taken into consideration in the movement of the true course ground speed pointer 35 and the 13 total distance pointer 54 for both of these pointers are actuated from the lever B.

It will be remembered that when the link I46 is actuated by the rotation of the wind velocity knob I67, link I35 mounted on the pin I38 of the link I46 actuates the Wire I42 throu h t multiplying mechanism shown in Fig. 4B; that is, assuming that pins I34 and I39 are not in alignment with each other. It will also be remembered that the wire I42 controls the position of pin 22 of lever B, that rack 2 controls the position of pin I of lever 6, and that wire 1! controls the position of pin 25 of lever 20, so that the pin 24 of lever 20 is controlled by the wire I42, the wire II, and the rack 2, and the movement of this pin 24 controls the true course ground speed pointer 38 and the total distance pointer 54.

However, both pins 22 and 25 are not always moved when the wind velocity knob I6! is rotated. For instance, suppose the wind direction knob IE is set as shown in Fig. 1. The pin I34 will then be a considerable distance below the pin I39 as shown in Fig. 4, while the pin III will be in alignment with the pin I22. If now the wind velocity knob IEI were rotated from its zero position the multiplying mechanism shown in Fig. 4B will actuate the Wire I42 and lower the pin 22; but since the pins III and I22 are in alignment with each other, the multiplying mechanism shown in Fig. 4A will not actuate the wire I25 and the pin 25 remains stationary. If the wind direction knob I55 were rotated 90 clockwise from the position shown in Fig, 1, the pin I34 would be raised into alignment with pin I39, so that the wind velocity knob I6! would impart no motion to pin 22. However, when knob I65 is rotated, as above described, the pin III would be lowered below the pin I22 as shown in Fig. 4A; and if knob I5! were then rotated from its zero position, the wire I25 would be actuated to lower the pin 25.

If the wind direction knob I55 were rotated 180 from the position shown in Fig. 1, the pin I34 would be raised as much above pin I39 as it is below it in Fig. 4B, while pin III would be moved into alignment with its pin I22. If now the wind velocity knob I61 were actuated, the pin 25 remains stationary while the pin 22 is raised- If the wind direction knob I65 were rotated clockwise 270 from its position shown in Fig. 1, the pin I39 would be in alignment with pin I34 while pin III would be raised above the pin I22. If now the wind velocity knob I55 were rotated from its zero position the pin 22 would remain stationary and pin 25 would be lowered,

However, when the wind direction knob I65 is moved to any position other than the four positicns above mentioned, and the wind velocity knob I6? is actuated, both pin 22 and pin 25 would be actuated in accordance with the position into which knob I85 i set and in accordance with the extent of rotation of wind velocity knob I61. In other words, the pin 25 is not actuated by the wind velocity knob IS! in two cases; that is, when the wind direction knob I65 is in the position shown in Fig. 1 or when it is rotated 180 from that position; but in both of these cases the pin 22 is actuated when the Wind velocity is actuated. Conversely the pin 25 is actuated by the rotation of the knob I6! when the wind is blowing at a right angle to the direction of the travel of the ship, and the pin 22 is not actuated under these conditions.

It is therefore apparent that the true course ground speed pointer 36 is controlled by (1) true airspeed knob I63 as shown in Fig. 3, (2) wind direction knob I65 as shown in Fig. 4, and (3) wind velocity knob I6! as shown in Fig. 4. The true course in degrees (C), the wind direction (W), and the drift angle in degrees (D) are all set by the knob I65 and the disc I66. As above stated, the true course ground speed may be calculated by the following formula:

Vg=Va+Va(COS D-1) i-Vw cos(C'W) Formula #2 VB. is indicated by the vertical movement of rack 2.

Cos D1 corresponds to the vertical movement of wire 9| and is indicated by the relative positions of pins I3 and pin I4, cos D--1 being 0 when the pins I3 and I4 are in direct alignment.

The multiplication of Va by (cos D1) is accomplished on arms and links 58, III, II, and I5, which is the multiplying mechanism shown in Fig. 3D.

Vw is accomplished by the vertical movement of point I38.

Cos (C-W) is accomplished by the movement of wire I I I controlled by point I I2.

The multiplication of Vw by cos (C-W) is accomplished on the multiplying mechanism shown in Fig. 4B.

The addition of {Va}+{Vw cos(CW)} is accomplished on lever B.

The addition of which is Vg, is accomplished on lever 20.

The total distance pointer 54 is controlled by (1) true airspeed knob I63 as shown in Fig 3, (2.) wind direction knob I65 as shown in Fig. 4, (3) wind velocity knob I61 as shown in Fig. 4, and (4) time as shown in Fig. 3. It will be noted that the first three of these elements are identical with the parts used in the calculation of the true course ground speed and that in calculating total distance, time has been taken into consideration. Obviously the total distance (d) is the true course ground speed V multiplied by time (t) That is, d=Vgt. Formula #4.

If it is desired to know the time it will take to fiy a known total distance, the operator would set the true airspeed knob I53, the wind direction knob I55 and the wind velocity knob I67. He would then set the time knob I34 until the total distance pointer 54 indicated the known total distance, and he would then read the time on the dial behind the knob I84.

As above explained, the true course ground speed V is calculated by lever 20, which actuates lever 26 carrying pin 39, so that Vg is accomplished by the vertical movement of pin 35. The time factor is entered by the movement of pins I05 or 45, Fig. 3. The multiplication of Vg by t, which is (d), is accomplished by the multiplying mechanisms 31, 49, 43, 44, and 47 shown in Fig. 3A.

The indicated airspeed pointer I9 is controlled by (1) true airspeed knob I63 as shown in Fig. 3, (2) altitude knob I68 as shown in Fig. 5, and (3) air temperature knob III! as shown in Fig. 5. The indicated airspeed may be calculated by the following formula:

Vi=Va+Va (a%1) Formula #3 Va is accomplished by the vertical movement of pin 51.

(T -1 is denoted by the relative positions of 38 pins 65 and 66, the pin '65 being controlled by the air temperature and altitude knobs.

The multiplication of Va by (a 1) is accomplished on arms and links 55, s2, 63, ill, and M2, as shown in Fig. 3C.

The addition of Va-l-Va (o'%1), which is V1 on indicated airspeed, is accomplished on link ii through wire 69.

The pilot, being familiar with his plane, would know the best indicated airspeed to fly so that in practice he would determine true airspeed by first entering the known values for air temperature by knob ill! and altitude by knob Hi8 and would then rotate the true airspeed knob lei,

until the indicated airspeed pointer iii showed theproper value for the operation of that plane. He would then read the true airspeed on the dial behind the true airspeed knob 563.

The'drift angle pointer as is controlled by (1) true airspeed knob its as shown in Fig. 3, (2) wind direction knob lei; as shown in Fig. 4, and (3) wind velocity knob it'll as shown in Fig. 4.

The drift angle (D) may be computed by the following formula:

V smf- W) li ormula #1.

The knob H33 controls the true airspeed setting (Va). The knob 55 controls the wind direction setting (W), as well as course (C), and the wind velocity knob I61 controls the wind velocity setting (Vw).

Sin is accomplished by pin 96.

Vw is accomplished by the vertical movement of rack MG.

Sin (CW) is accomplished by the movement of wire [09 actuated by pin i it.

The multiplication of Vw by sin (CW) is accomplished on arms and links H iiii, M8, M9, and I23 as shown in Fig. 4A.

Va is accomplished by the vertical. movement of link 55 actuated by rack 2.

The multiplication of vw sin cm Sinby V which is the angle D, is accomplished by the movement of pin 98 on arm 86.

With the arrangement of the variables as incorporated in this flight computer, it becomes possible to calculate a wide variety of problems. As an illustration, suppose the operator enters the values for true course, wind direction, wind velocity, altitude, air temperature, and time of flight and knows the desired indicated airspeed. If he will now turn the true airspeed knob until the correct indicated airspeed is indicated, the machine will calculate the following results: Drift angle, true course ground speed, total distance fiown'and true airspeed.

As another example, suppose the operator enters the values for true course, wind direction, wind velocity, altitude, air temperature and time of flight and knows the total distance to be flown. If he will now adjust the true airspeed knob until the total distance pointer reads the correct total distance, the indicated airspeed pointer will show the necessary indicated air- 18 speed to be maintained in order to fly a given course in a specified time.

Obviously, many other problems can be solved with this calculator, and the above are given as simply representative examples.

Obviously the relative lengths of the various arms and levers and the position of the pivot points on which the various levers turn are material, but their relative lengths and positions are as shown in the drawings, the said drawings being made substantially to scale insofar as the relative lengths of the various levers and links and the position of their pivotal points are concerned.

I realize that many changes may be made in the specific form of the invention shown herein without departing from the spirit and scope thereof; and I, therefore, desire to claim the same broadly except as I may limit myself in the following claims.

Having now described my invention, I claim:

1. In 'a computer, an air temperature setting means, an altitude setting means, a multiplying mechanism, means to actuate a part of said multiplying mechanism according to the setting of both of said setting means,a true airspeed setting means to actuate another part of said multiplying mechanism, said multiplying mechanism serving as a means to multiply a function of altitude and air temperature by true airspeed, a lever, means to move one end of said lever by said multiplying means, means to move the other end of said lever according to the value set by true airspeed setting means, an indicator and means to operate said indicator from said lever.

2. in a computer, a wind direction setting means, means controlled thereby to determine the value sin (C-W) where W is the direction the wind is blowing relative to north and C is the direction in which a movable object heads, means to enter the wind velocity value Vw, means controlled by said two means to multiply Vw by sin (Cl/V), means to enter the true airspeed Va, means controlled by said true airspeed entering means and by said multiplying means to divide Vw sin (C--W) by Va, means for converting the value V sin C W a to the value of the angle represented thereby, and an indicator to indicate the resulting value.

3. In a computer, a calculating mechanism comprising a value indicator, a plurality of settable value entering elements, a device manually settable to register the result of a calculation, and mechanism for determining the correct position to which said device should be set for any given values entered by said value entering elements and indicated by said indicator, respectively, said mechanism including a lever pivotally connected intermediate its ends to said indicator, an operating connection between one end of said lever and said device, a movement multiplying linkage, an operating connection between the other end of said lever and said multiplying linkage, an operating connection between said device and said multiplying linkage, a second lever pivotally connected intermediate its ends to said multiplying linkage, an operating connection between one of said value entering elements and one end of said second lever, and an operating connection between the other of said value entering elements and the opposite end of said second lever.

17 4. In a computer of the class described, calculating mechanism comprising a value indicator, a plurality of settable value entering elements, a device manually settable to register the result of a calculation, and mechanism for determining the correct position to which said device should be set for any given values entered by said value entering elements and indicated by said indicator, respectively, including means controlled by said device for imparting to said indicator an adjustment directly proportional to the magnitude of the setting movement of said device, means controlled b said value entering elements for adding values entered by the setting thereof, and means controlled by said device and by said adding means, jointly, for imparting to said indica tor an adjustment proportional to the magnitude of the product of a multiplication of the sum of the values entered by the setting of said value entering element multiplied by the value registered by said result registering device. Y

5. In a computer, setting means to enter velocity, a first lever having one end actuated an amount directly proportional to the value entered by said setting means, a second velocity setting means, a wind direction setting means, means to multiply the value entered by said second velocity setting means by a cosine value dependent upon the extent of the actuation of said wind direction setting means, means to actuate the other end of said lever an amount corresponding to said product, a second lever having one end thereof pivoted to an intermediate part of said first lever, means jointly controlled by all of said setting means for adjusting the other end of said second lever, and an indicator actuated by said second lever.

6. In a computer, setting means to entervelocity, a first lever having one end actuated an amount directly proportional to the value entered by said setting means, a second velocity setting means, a wind direction setting means, means to multiply the value entered by said second velocity setting means by a cosine value dependent upon the extent of the actuation of said wind direction setting means, means to actuate the other end of said lever an amount corresponding to said product, a second lever having one end thereof pivoted to an intermediate part of said first lever, means controlled by all of said setting means to actuate the other end of said second lever an amount corresponding to correlated values of all three of said setting means, a third lever actuated by said second lever, means to enter time, means to multiply the value of the movement of the third lever by the value entered by said time setting means and an indicator actuated by said last named multiplying means.

7. In a computer, means for entering a linear value, means for entering an angular value, a pair of multiplying mechanisms each comprising a pair of adjustable input members, an output member, and mechanism for transmitting the movement of each input member to said output member in an amount so modified by the adjustment of the other input member as to position the output member in accordance with the product of values represented by the adjustment of the input members, means controlled by said lincar value entering means for entering identical multiplicand values in both of said multiplying mechanisms, and means controlled by said angular value entering means for entering complementary multiplier values in said multiplying mechanisms respectively; whereby the output members of said multiplying mechanisms regis-.

18 ter vectorial components of the linear value entered by said linear value entering means.

8. In a trigonometrical computer, separate means for entering linear values corresponding to two sides of a triangle, means for entering an angular value corresponding to the supplement of a non-included angle of said triangle, multiplying means controlled by one of said linear value entering means and by said angular value entering means, dividing means controlled by the other of said linear value entering means and by said multiplying means, and means controlled by 'said dividing means for registering an angular value corresponding to the other non-included angle of said triangle.

9. In a trigonometrical computer, separate means for entering linear values corresponding to two sides of a triangle, means for entering an angular value corresponding to the supplement of a non-included angle of said triangle, a pair of multiplying mechanisms, means controlled by one of said linear value entering means for entering identical multiplicand values in both of said multiplying mechanisms, means controlled by said angular value entering means for entering the values of the sine and cosine of said angular value in said multiplying mechanisms, respectively, dividing means controlled by the other of said linear value entering means and by a first one of said multiplying mechanisms, multiplying means controlled by said other of said linear value entering means and said dividing means, and means for adding the products registered by said multiplying means and by the second one of said multiplying mechanisms and the linear value entered by the said other of said linear value entering means and registering a linear value corresponding to the third side of said triangle.

10. In a computer, means for entering a linear value, means for entering an angular value, a pair of multiplying mechanisms each comprising a pivotally supported guide link, a first movable link having a pivotal connection with said guide link radially spaced from the pivotal support thereof, a second movable link having a pivotal connection with said first link radially spaced from the pivotal connection of said first link with said guide link, and a movable member having a pivotal connection with said second link radially spaced from the pivotal connection between said links; all of said radial spacings being equal; means controlled by said linear value entering means for imparting identical movements to one pivotal connection between said links in each of said multiplying mechanisms, means controlled by said angular value entering means for imparting respectively complementary movements to the other pivotal connection between said links in each of said multiplying mechanisms, and means controlled by the respective movable members of said multiplying mechanisms for registering respective vectorial components of the linear value entered by said linear value entering means,

11. In a computer, means for entering a linear value, means for entering an angular value, a pair of multiplying mechanisms each comprising a pivotally supported guide link, a first movable link having a pivotal connection with said guide link radially spaced from the pivotal support thereof, a second movable link having a pivotal connection with said first link radially spaced from the pivotal connection of said first link with said guide link, and a movable member having a pivotal connection with said second link radially spaced from the pivotal connection between said links; all of said radial spacings being equal; means controlled by said linear value entering means for imparting identical movements to one pivotal connection between said links in each of said multiplying mechanisms, means controlled by said angular value entering means for imparting to the other pivotal connection between said links in one of said multiplying mechanisms a movement proportionate to the sine of the angular value entered by said angular value enterin means, means controlled by said angular value entering means for imparting to the other pivotal connection between said links in the other of said multiplying mechanisms a movement proportionate to the cosine of the angular value entered by said angular value entering means, and means controlled by the respective movable members of said multiplying mechanisms for registering respective vectorial components of the linear value entered by said linear value entering means.

LEWIS W. IMM.

REFERENCES CITED The .following references are of record in the -'file of this patent:

UNITED STATES PATENTS Number Name Date 1,038,350 Goss -1 Sept. 10, 1912 1,383,660 Proctor July 5, 1921 1,743,239 Ross Jan. 14, 1930 1,910,093 Colvin May 23, 1933 2,022,275 Davis Nov. 26, 1935 2,077,523 .Hug Apr. 20, 1937 2,116,508 Colvin May 10, 1938 2,179,822 Imm Nov. 14, 1939 2,224,774 ,Tauschek Dec. 10, 1940 2,319,322 Hefel May 18, 1943 FOREIGN PATENTS Number Country Date 113,136 Great Britain Feb. 7, 1918 291,841 Great Britain June 5, 1928 796,214 France Jan. 17,, 1936 

